In 1933, Harteck went to do research with Ernest Rutherford at the University of Cambridge. Upon his return from England in 1934, he became an ordinarius professor and director of the physical chemistry department at the University of Hamburg. From 1937, he was an advisor to the Heereswaffenamt (HWA, Army Ordnance Office). In April 1939, along with his teaching assistant Wilhelm Groth, Harteck made contact with the Reichskriegsministerium (RKM, Reich Ministry of War) to alert them to the potential of military applications of nuclear chain reactions. From that year, his department as a whole did research for the HWA, with emphasis on uranium isotope separation. From 1940, with Hans Suess, his focus was on the use of heavy water as a neutron moderator. In 1941, his department constructed a conversion unit for Norsk Hydro for the catalytic production of heavy water. In 1942, especially with the help of Werner Heisenberg, Harteck circumvented an appointment in Russia. In February 1943, Harteck and his colleague Johannes Jensen suggested a new type of centrifugal isotope separation, which was adopted by the Anschütz Company. Under his supervision Wilhelm Groth conducted the last enrichment experiments with the ultracentrifuge in Celle, a small town 120 km south of Hamburg. In late spring 1945, Harteck was arrested by the allied British and American Armed Forces and incarcerated at Farm Hall for six months under Operation Epsilon. In 1946, upon his return from incarceration, he became director of the chemistry department at the University, a position he held until 1950.[1][2]